Brake Pedal Sinking to floor

[GAINMOB]

my local repair shop replaced my ABS pump and as far as i know they got the part aftermarket

 

[04WHITEEDDIE]

I checked the vacuum hose at the check valve ...getting ~20 in Hg at idle. The check valve is new (came with the new brake booster.) Just to be sure ,I pulled it out and checked it ...only draws air 1 way...seems to be working fine.

Without the engine running, brake pedal has some firmness but sinks slowly with firm foot pressure. As soon as i start the engine, the pedal goes right the floor without much foot pressure. After the turn engine off, I can depress the pedal to the floor easily 1 time and then it starts to firm up .

My brake booster rod does'nt have the "offset" where it connect to the pedal.

 

[04WHITEEDDIE]

Gain-Mod...I searched the internet , I cant find anyone that sells new ABS pump (OEM or aftermarket)..seems to be a discontinued part. Original part was manufactured by Ate .When did you get yours replaced?

 

[BlackCoffee]

It's time to find a reliable junk yard that will let you pull parts. The good news is that when you pull it yourself, they usually only charge 15-25 bucks depending on the part.

 

[Tocapet]

I had a brake booster go bad in a '73 Jeep Wagoneer that I had. It was leaking vacuum. Stepping on the brake pedal caused the engine to stumble & run rough at a stoplight. Couldn't find a replacement anywhere, so I just took the booster off and mounted the master cylinder right on the firewall. This gave me standard non-power brakes. Drove it like that, passed inspection like that & sold it like that. Sorry to be off-topic here, but on some vehicles that can be an option.

 

[juan214]

Might be late or if it still persist. I had the same issue on my 99. Take a look at the rear brake line. Specifically the one on the frame rail above the rear end. I had a tiny pin hole in it. It never leaked onto the ground because of the location of the leak. The front brakes / line held the pressure and slowly drop until the front brakes slowed and stopped the truck. I only do city driving around town as of late. I basically ignored it.

How did i figure I had no rear brakes? Yearly Safety inspection Parking Brake check and adjustments. While in the air and after adjustment applied the brakes and the rears kept spinning.

 

[Drae]

Old hydraulic brake hoses can cause a soft pedal too. If you haven't replaced those, it's worth a shot. I have an 03 too and it's about time for me to change mines. A little mushy also.

 

[04WHITEEDDIE]

Thanks , I was thinking about the hoses too...16 years old...it maybe time.

 

[riphip]

Rockauto.com is where I bought mine. Went ahead and replaced them all. Like you, 16 years old